1. Field of the Invention
The present invention relates to a display device, and more particularly, to a borderless type three-dimensional (3D) liquid crystal display (LCD) device which facilitates to display 3D images and to enhance a sense of beauty.
2. Discussion of the Related Art
A display device has been continuously developed to satisfy various requirements such as large-sized screen and thin profile. Especially, there is the explosive increase in flat type display devices having advantages of thin profile, lightness in weight, and low power consumption.
The flat type display device may include a liquid crystal display device (LCD), a plasma display panel (PDP), a field emission display device (FED), a light-emitting diode display device (LED), and etc.
Among the various flat panel display devices, the LCD device is widely used owing to various advantages, for example, technical development for the mass production, easiness of driving means, low power consumption, and high-quality resolution.
The LCD device comprises a liquid crystal panel with a plurality of liquid crystal cells (pixels) arranged in a matrix configuration; and a driving circuit for driving the liquid crystal panel. As light transmittance is adjusted pixel-by-pixel in accordance with an input video signal, an image is displayed on the LCD device.
There are the plural liquid crystal cells defined by crossing a plurality of gate lines and a plurality of data lines of the liquid crystal panel. Each liquid crystal cell is provided with pixel electrode and common electrode for applying an electric field. Each of the liquid crystal cells is switched via a thin film transistor (TFT).
The driving circuit includes a gate driver, a data driver, a timing controller, a common voltage supplier, and a backlight driver.
The timing controller generates a gate control signal in accordance with an input clock signal, and supplies the generated gate control signal to the gate driver. Also, the timing controller generates a data control signal in accordance with the input clock signal, and supplies the generated data control signal to the data driver. In addition, the timing controller aligns the input video signal to digital video data, and then supplies the aligned digital video data to the data driver.
The gate driver generates a scan signal in accordance with the gate control signal supplied from the timing controller, and supplies the generated scan signal to the gate lines.
The data driver converts the digital video data into an analog data voltage in accordance with the data control signal supplied from the timing controller, and supplies the analog data voltage to the data lines.
The common voltage supplier supplies a common voltage (Vcom) to the liquid crystal cell.
The backlight driver drives a light source (backlight) for supplying light to the liquid crystal panel.
In the LCD device, an alignment of liquid crystal is changed depending on a voltage formed between the pixel electrode and the common electrode pixel-by-pixel. Thus, transmittance of light emitted from the backlight unit can be controlled through the alignment of liquid crystal, to thereby display the image.
Recently, a user's demand for a stereoscopic image is rapidly increased so that an LCD device capable of displaying 3D (3-dimensional) image as well as 2D (2-dimensional) image is actively developed.
The LCD device displaying 3D image can realize the 3D image through a difference in viewing between both eyes of the user (binocular parallax display).
There have been proposed a shutter glass method using stereoscopic glasses, and a patterned retarder method using polarizing glasses.
FIG. 1 illustrates a method of realizing 3D image by the use of shutter glass according to the related art.
Referring to FIG. 1, the method of realizing 3D image by the use of shutter glass according to the related art is to use the user's binocular parallax.
After 2D left image and 2D right image, which are different from each other, are respectively viewed by the left and right eyes of the user, two of the 2D images are integrated so that the integrated image is discerned as the 3D image by the user.
For this, a liquid crystal panel 10 separately displays 2D images for the left viewing and right viewing with a difference in time. In this case, rising or falling of liquid crystal is not completely finished for a preset period of time (frame) due to slow response speed of liquid crystal. Thus, luminance may be not uniform between lower and upper end portions of the liquid crystal panel 10.
Also, since the shutter glass is turned-on/off by the use of liquid crystal, a response speed of the shutter glass becomes slow. Thus, even though the shutter glass is turned-off at an end point of a vertical period of 1 frame, the shutter glass is not completely closed until when image data is displayed on the upper end portion of the liquid crystal panel.
Accordingly, there is the difference in response speed of liquid crystal between the lower and upper end portions of the liquid crystal panel. Also, the left image and right images are not separated from each other together with the luminance nonuniformity, that is, crosstalk occurs, thereby deteriorating the picture quality of 3D image. If the user watches the 3D image with the crosstalk occurrence for a long time, the user is liable to feel dizzy.
FIG. 2 illustrates an LCD device of patterned retarder method using polarizing glasses according to the related art.
Referring to FIG. 2, an LCD device of patterned retarder method includes a liquid crystal panel 10 for displaying an image; and a patterned retarder layer which enables the user to discern 3D image by patterned-retarding the image displayed on the liquid crystal panel 10.
The liquid crystal panel 10 includes lower and upper substrates confronting each other with a liquid crystal layer interposed therebetween. A lower polarizing plate (lower polarizing film) 12 is positioned at a lower side of the liquid crystal panel 10, and an upper polarizing plate (lower polarizing film) 14 is positioned at an upper side of the liquid crystal panel 10.
The patterned retarder layer retards the image displayed on the liquid crystal panel 10. The patterned retarder layer includes a transparent glass 20; first and second polarizers 24 and 26 formed under the transparent glass 20, wherein the first and second polarizers 24 and 26 circularly polarize light leftward or rightward; and a black matrix 22 for blocking the light.
The patterned retarder layer displays the left image by retarding the leftward circularly polarized light which is emitted from the pixels corresponding to the half of all pixels included in the liquid crystal panel 10 through the first polarizer 24. For example, the first polarizer 24 may leftward circularly polarize the light which is emitted from the pixels in the odd-numbered lines of the liquid crystal panel 10.
Also, the patterned retarder layer displays the right image by retarding the rightward circularly polarized light which is emitted from the pixels corresponding to the other half of all pixels included in the liquid crystal panel 10 through the second polarizer 26. For example, the second polarizer 26 may rightward circularly polarize the light which is emitted from the pixels in the even-numbered lines of the liquid crystal panel 10.
Thus, the user discerns the 3D image by the left image and the right image separately displayed.
The related art LCD device satisfies the user's functional requirement by displaying the 3D image in the above shutter glass method and patterned retarder method.
Recent research is particularly required on design of the LCD device to satisfy the sense of beauty as well as the function requirement.
Consequently, efforts for minimizing the thicknesses (slimness) of LCD devices are continuously being made, and research is being conducted on a design with enhanced sense of beauty that can induce consumers to buy by appealing to consumers' sense of beauty.
For example, a borderless type LCD device for minimizing the border area and step difference has been researched and studied.
FIG. 3 illustrates a borderless type LCD device according to the related art.
Referring to FIG. 3, the borderless type LCD device according to the related art includes a liquid crystal panel 10 for displaying an image; a guide panel 16 on which the liquid crystal panel 10 is placed; a bottom cover 18 having a vertical part and an extended part, wherein the vertical part covers lateral sides of the liquid crystal panel 10, and the extended part covers a predetermined portion of an upper side of the liquid crystal panel 10; and a tempered glass 30 provided on the bottom cover 18.
In this case, a lower polarizing plate 12 is provided on a lower surface of the liquid crystal panel 10, and an upper polarizing plate 14 is provided on an upper surface of the liquid crystal panel 10.
In the borderless type LCD device according to the related art, the tempered glass 30 is provided on the extended part of the bottom cover 18 for covering the upper edge of the liquid crystal panel 10. Then, the bottom cover 18 and the tempered glass 30 are bonded to each other by an adhesive 32.
For viewing the LCD device, the consumer's requirement for the sense of beauty may be satisfied to some extent owing to the minimized border area and step difference.
However, as shown in FIG. 3, the tempered glass 30 is provided on the extended part of the bottom cover 18 for covering the lateral sides and the predetermined portion of the upper side of the liquid crystal panel 10, there is an air gap between the liquid crystal panel 10 and the tempered glass 30.
The borderless type LCD device according to the related art may have phase retardation due to the difference in refraction by the air gap between the liquid crystal panel 10 and the tempered glass 30. Thus, light being emitted from the liquid crystal panel 10 and being incident on the tempered glass 30 is changed in its phase, whereby the display image is distorted.
In order to display the 3D image on the borderless type LCD device, a patterned retarder layer should be additionally formed on the liquid crystal panel 10, thereby causing the complicated manufacturing process and the increased manufacturing cost.
For avoiding the above problems of the patterned retarder method, the shutter glass method may be used. However, in case of the shutter glass method, the increase of cost is unavoidable due to the shutter glasses. Also, the picture quality of display image may be deteriorated by the above crosstalk.